Problem: Christopher is 66 years old and Vanessa is 15 years old. How many years will it take until Christopher is only 4 times as old as Vanessa?
Answer: We can use the given information to write down an equation about how many years it will take. Let $y$ be the number of years that it will take. In $y$ years, Christopher will be $66 + y$ years old and Vanessa will be $15 + y$ years old. At that time, Christopher will be 4 times as old as Vanessa. Writing this information as an equation, we get: $66 + y = 4 (15 + y)$ Simplifying the right side of this equation, we get: $66 + y = 60 + 4 y$ Solving for $y$ , we get: $3 y = 6$ $y = 2$.